Antibiotic analysis using Electro-Filtering Paper Spray Ionization.

In this work, we analyzed the performance of the Electro-Filtering Paper Spray Ionization (EFSI) method for detecting compounds in unprocessed samples. A relatively rigid and electrically conductive copper filter was used as a substrate to insure sufficient and efficient sample-solvent extraction and to increase the conductivity for paper spraying. The method was demonstrated as applicable for indirect high-throughput analysis of large-volume unprocessed samples, which is not possible with conventional nanoESI or direct paper spray methods. The new method can generate different desired ion signals for a wide range of compounds by selecting different extraction solvents. Moreover, key parameters related to extraction efficiency were optimized in detail to obtain the most satisfactory extraction efficiency during antibiotic analysis. Finally, under optimal conditions, the EFSI method was successfully used to detect four antibiotics in animal products of egg, chicken, and chicken liver, exhibiting good reproducibility with calibration curves between 81.6% and 96.3%, and R values above 0.99. Recoveries of 75.0%ￚ94.6% were obtained for the four antibiotics. Hence, the proposed EFSI-MS is a successful, economical, rapid, and high-throughput method that is effective for both unknown and targeted extraction of unprocessed samples by mass spectrometric analysis.